1986 Ford F-150 during issue

I have a 1986 Ford F-150 with a 5.0 fuel injected motor. Today I was driveing itís about 42 degrees out and it was ode long funny and then when I go to stop it wonít to die and died on me once. I changed the iac valve 6 mounts ago CSUís wit was doing this same thing now Iím wondering what it could be? Can it be the EGR Valve or something I else? This just started in the cold today. If I put it in nutral and rev a little while stoping then it wonít die.